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secondary 4 | Chemistry
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Jonathan
Jonathan

secondary 4 chevron_right Chemistry chevron_right Singapore

Why is the answer C?

Date Posted: 2 years ago
Views: 436
J
J
2 years ago
2 and 3 are correct because they involve the reaction of an ammonium salt and a base/alkali

Ammonium salt + metallic base/alkali → metallic salt + ammonia + water


For 2,

2 NH4Cl (aq) + Ca(OH)2 (aq) → CaCl2 (aq) + NH3 (g) + H2O (l)

For 3,

(NH4)2SO4 (s) + 2KOH (s) → K2SO4 (s) + 2NH3 (g) + 2H2O (g)

(The heating should be strong enough to cause the water to boil/evaporate)



1 is basically the nitrate test.


3 NaNO3 (aq) + 8 Al (s) + 5 NaOH [(aq) or (s) since state is not given] + 18 H2O (l, comes from the aqueous solution)→8 Na[Al(OH)4] (aq) + 3 NH3 (g)


For 4, nothing much happens.

In NH4Cl (aq) and HCl (aq) , you basically have a mix of NH4+ ions , H+ ions and Cl- ions dissolved in water.

There is no displacement or any reaction.

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